Offset angle calibration method, posture detection method, offset angle calibration system, and posture detection system

Abstract

To suppress measurement errors in an offset angle of a work machine.SOLUTION: An offset angle calibration method for calibrating an offset angle of a work device of a work machine comprises: a position information acquisition step of acquiring position information of a predetermined position of the work machine using a measuring device in a plurality of offset postures in which only offsetting in left and right direction is performed while the work machine is fixed in a predetermined posture; a first offset angle calculation step of calculating a first offset angle in each offset posture based on the position information; a calibrating second offset angle acquisition step of acquiring a second offset angle in each offset posture based on detection values in the plurality of offset postures by an angle sensor mounted on the work machine and detecting an offset angle of the work machine; and an error calculation step of calculating a measurement error of the angle sensor based on the first offset angle and the second offset angle in the plurality of offset postures.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to an offset angle calibration method, a posture detection method, an offset angle calibration system, and a posture detection system.

Background Art

[0002] In the technical field related to work machines, a hydraulic excavator equipped with an offset boom and an angle sensor for detecting an offset angle, as disclosed in Patent Document 1, is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, a measurement error of the offset angle may occur due to an attachment error of the angle sensor.

[0005] An object of the present disclosure is to suppress a measurement error of the offset angle of a work machine.

Means for Solving the Problems

[0006] According to the present disclosure, there is provided an offset angle calibration method for calibrating the offset angle of a working machine of a working machine, the method comprising: a position information acquisition step of acquiring position information of a predetermined position of the working machine using a measuring device in a plurality of offset postures in which only an offset in the left-right direction is performed while the working machine is fixed in a predetermined posture; a first offset angle calculation step of calculating a first offset angle in each offset posture based on the position information; a second offset angle acquisition step for calibration of acquiring a second offset angle in each offset posture based on detection values in a plurality of offset postures by an angle sensor mounted on the working machine and detecting the offset angle of the working machine; and an error calculation step of calculating a measurement error of the angle sensor based on the first offset angle and the second offset angle in a plurality of offset postures.

Effect of the Invention

[0007] According to the present disclosure, the measurement error of the offset angle of the working machine is suppressed.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 11

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Figure 14

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Figure 17

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Figure 22

Figure 23

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiments. The components of the embodiments described below can be combined as appropriate. Also, some components may not be used.

[0010] In the embodiment, the terms “left”, “right”, “front”, “rear”, “upper”, and “lower” are used to describe the positional relationship of each part. These terms indicate the relative position or direction based on the center of the working machine. The left - right direction, the front - rear direction, and the upper - lower direction are orthogonal.

[0011] [Working Machine] FIG. 1 is a perspective view showing a working machine 1 according to the embodiment. FIG. 2 is a side view showing the working machine 1 according to the embodiment. FIG. 3 is a front view showing the working machine 1 according to the embodiment. The working machine 1 operates at a work site. In the embodiment, the working machine 1 is a hydraulic excavator. The working machine 1 includes a working device 3. In the embodiment, the working device 3 is an offset - type working device having an offset boom. As shown in FIGS. 1, 2, and 3, the working machine 1 includes a vehicle body 2 and a working device 3.

[0012] The vehicle body 2 is the working machine body of the working machine 1. The vehicle body 2 includes a revolving body 11, a traveling body 12, and a blade 13. The revolving body 11 is disposed above the traveling body 12. The revolving body 11 is rotatably supported by the traveling body 12. The revolving body 11 rotates about a swivel axis RX. The revolving body 11 has a floor 14, a driver's seat 15 disposed on the floor 14, and a roof 16 disposed above the driver's seat 15. The traveling body 12 has a pair of crawler belts 12A. The working machine 1 travels by the rotation of the crawler belts 12A. The blade 13 is disposed in front of the traveling body 12. The blade 13 is liftable by a hydraulic actuator.

[0013] The working machine 3 is attached to the revolving body 11 so as to be offsettable in the left - right direction. The working machine 3 includes a first boom 4 connected to the revolving body 11, a second boom 5 connected to the first boom 4, a swing bracket 6 connected to the second boom 5, an arm 7 connected to the swing bracket 6, and a bucket 8 connected to the arm 7. The bucket 8 is an example of a working tool. The first boom 4, the second boom 5, and the swing bracket 6 constitute an offset boom.

[0014] The first boom 4 is attached to the revolving body 11 so as to be rotatable in the vertical direction. The revolving body 11 and the first boom 4 are connected via a boom pin 17. The first boom 4 is supported by the revolving body 11 so as to be rotatable about a rotation axis AX1.

[0015] FIG. 4 is a diagram showing the connection structure between the first boom 4 and the second boom 5 according to the embodiment. The second boom 5 is rotatably attached to the first boom 4. The second boom 5 is attached to the first boom 4 so as to be swingable in the left - right direction. The first boom 4 and the second boom 5 are connected via an offset pin 18. The second boom 5 is supported by the first boom 4 so as to be rotatable about an offset axis BX1.

[0016] The swing bracket 6 is rotatably attached to the second boom 5. The swing bracket 6 is attached to the second boom 5 so as to be swingable in the left - right direction. The second boom 5 and the swing bracket 6 are connected via a bracket pin 19. The swing bracket 6 is connected to the second boom 5 so as to be rotatable about the offset axis BX2.

[0017] The arm 7 is rotatably attached to the swing bracket 6, which is the tip of the offset boom, in the vertical direction. The swing bracket 6 and the arm 7 are connected via an arm pin 20. The arm 7 is supported by the swing bracket 6 so as to be rotatable about the rotation axis AX2.

[0018] The bucket 8 is rotatably attached to the tip of the arm 7 in the vertical direction. The arm 7 and the bucket 8 are connected via a bucket pin 21 and a link 22. The bucket 8 is supported by the arm 7 so as to be rotatable about the rotation axis AX3.

[0019] The first boom 4 and the swing bracket 6 are connected via an offset stay 9. The offset stay 9 is rotatably connected to each of the first boom 4 and the swing bracket 6.

[0020] The rotation axis AX1, the rotation axis AX2, and the rotation axis AX3 are parallel. The offset axis BX1 and the offset axis BX2 are parallel. The rotation axes AX1, AX2, AX3 and the offset axes BX1, BX2 are orthogonal. The rotation axes AX1, AX2, AX3 and the axis parallel to the slewing axis RX are orthogonal. The left - right direction is parallel to the rotation axes AX1, AX2, AX3. The left - right direction is the vehicle width direction of the slewing body 11. The up - down direction is parallel to the slewing axis RX. The front - rear direction is orthogonal to both the rotation axes AX1, AX2, AX3 and the slewing axis RX.

[0021] The working machine 3 is operated by a hydraulic cylinder. The working machine 1 has a first boom cylinder 23 for operating the first boom 4, a second boom cylinder 24 for operating the second boom 5, an arm cylinder 25 for operating the arm 7, and a bucket cylinder 26 for operating the bucket 8.

[0022] The first boom cylinder 23 is connected to each of the revolving body 11 and the first boom 4. When the first boom cylinder 23 expands and contracts, the base end portion of the first boom 4 rotates about the rotation axis AX1, and the tip end portion of the first boom 4 moves in the vertical direction.

[0023] The second boom cylinder 24 is connected to each of the second boom 5 and the swing bracket 6. When the second boom cylinder 24 expands and contracts, the base end portion of the second boom 5 rotates about the offset axis BX1 and the base end portion of the swing bracket 6 rotates about the offset axis BX2, so that the second boom 5 swings in the left - right direction with respect to the first boom 4 and the arm 7 moves horizontally in the left - right direction.

[0024] The arm cylinder 25 is connected to each of the swing bracket 6 and the arm 7. When the arm cylinder 25 expands and contracts, the base end portion of the arm 7 rotates about the rotation axis AX2, and the tip end portion of the arm 7 moves in the vertical direction.

[0025] The bucket cylinder 26 is connected to each of the arm 7 and the bucket 8. When the bucket cylinder 26 expands and contracts, the base end portion of the bucket 8 rotates about the rotation axis AX3, and the cutting edge of the bucket 8 moves in the vertical direction.

[0026] [Drive System and Drive Control System] FIG. 5 is a block diagram showing the drive system 41 and the drive control system 42 of the working machine 1 according to the embodiment. The working machine 1 has a drive system 41 and a drive control system 42.

[0027] The drive system 41 includes a drive source 43 and a hydraulic pump 44. The drive source 43 is, for example, an internal combustion engine. Note that the drive source 43 may also be an electric motor or a hybrid mechanism of an engine and an electric motor. The hydraulic pump 44 is driven by the drive source 43 and discharges hydraulic oil. The hydraulic oil discharged from the hydraulic pump 44 is supplied to each of the first boom cylinder 23, the second boom cylinder 24, the arm cylinder 25, and the bucket cylinder 26.

[0028] The working machine 1 includes a first travel motor 45A, a second travel motor 45B, and a swing motor 46. The first travel motor 45A drives one crawler belt 12A. The second travel motor 45B drives the other crawler belt 12A. The swing motor 46 swings the swing body 11. The hydraulic oil discharged from the hydraulic pump 44 is supplied to each of the first travel motor 45A, the second travel motor 45B, and the swing motor 46. Note that in FIG. 5, one hydraulic pump 44 is illustrated, but a plurality of hydraulic pumps 44 may be provided.

[0029] The drive control system 42 includes an operation device 47 and an input device 48. Each of the operation device 47 and the input device 48 is disposed around the driver's seat 15. The operation device 47 receives an operation by an operator for driving the working machine 3, the swing body 11, and the traveling body 12, and outputs an operation signal corresponding to the operation. The operation device 47 includes, for example, a lever, a pedal, and a switch.

[0030] The input device 48 receives an operation by an operator for setting the control of the working machine 1, and outputs an operation signal corresponding to the operation. The input device 48 is, for example, a touch screen. Note that the input device 48 may include a lever or a switch.

[0031] The drive control system 42 includes a main controller 51, a storage device 52, and a control valve 53. The main controller 51 is programmed to control the working machine 1 based on the acquired operation signal. The main controller 51 includes a processor such as a CPU (Central Processing Unit), and a main memory including a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory). The storage device 52 is an example of a non-transitory processor-readable recording medium. The storage device 52 records computer instructions that are executable by the processor and control the working machine 1.

[0032] The main controller 51 acquires an operation signal from the operation device 47 and the input device 48. The main controller 51 controls the control valve 53 based on the operation signal. The control valve 53 may be a pressure proportional control valve. Note that the control valve 53 may be an electromagnetic proportional control valve. The control valve 53 controls the flow rate of the hydraulic oil supplied from the hydraulic pump 44 to the first travel motor 45A and the second travel motor 45B. Thereby, the working machine 1 travels according to the operation of the operation device 47. The control valve 53 controls the flow rate of the hydraulic oil supplied from the hydraulic pump 44 to the first boom cylinder 23, the second boom cylinder 24, the arm cylinder 25, and the bucket cylinder 26. The main controller 51 generates a command signal to the control valve 53 so that the first boom 4, the second boom 5, the swing bracket 6, the arm 7, and the bucket 8 each operate according to the operation of the operation device 47. The control valve 53 controls the flow rate of the hydraulic oil supplied from the hydraulic pump 44 to the swing motor 46. The main controller 51 generates a command signal to the control valve 53 so that the swing body 11 swings according to the operation of the operation device 47. The main controller 51 generates a command signal to the control valve 53 so that the working implement 3 offsets in the left-right direction with respect to the vehicle body 2 according to the operation of the operation device 47.

[0033] [Attitude Detection System] FIG. 6 is a block diagram showing a posture detection system 60 according to an embodiment. The work machine 1 has the posture detection system 60. The posture detection system 60 includes a GNSS receiver 61, a pair of GNSS antennas 62A and GNSS antenna 62B, a body IMU 63, a boom IMU 64, an arm IMU 65, a bucket IMU 66, an angle sensor 67, a posture detection controller 68, a storage device 69, a display input device 70, and a communication device 71.

[0034] The posture detection system 60 detects the position and orientation of the revolving body 11 using the Global Navigation Satellite System (GNSS). Each of the GNSS receiver 61, the GNSS antenna 62A, and the GNSS antenna 62B is arranged on the revolving body 11. As shown in FIG. 1, in the embodiment, the GNSS antenna 62A and the GNSS antenna 62B are arranged at a predetermined interval in the left-right direction. The GNSS receiver 61 receives a positioning signal from a satellite, calculates the positions of the GNSS antenna 62A and the GNSS antenna 62B based on the positioning signal, and creates vehicle position data. The vehicle position data includes the position information and orientation information of the revolving body 11 in the global coordinate system by GNSS. The posture detection controller 68 acquires the vehicle position data from the GNSS receiver 61. The GNSS antenna 62A and the GNSS antenna 62B may be arranged at a predetermined interval in the front-rear direction.

[0035] As shown in FIG. 1, the body IMU 63 is arranged inside the revolving body 11. The body IMU 63 acquires vehicle tilt angle data indicating the tilt angle of the revolving body 11. The vehicle tilt angle data includes the angle (pitch angle) with respect to the horizontal in the vehicle front-rear direction and the angle (roll angle) with respect to the horizontal in the vehicle left-right direction. The body IMU 63 outputs the vehicle tilt angle data to the posture detection controller 68.

[0036] As shown in FIG. 1, the boom IMU 64 is arranged on the first boom 4. The boom IMU 64 acquires boom tilt angle data indicating the tilt angle of the first boom 4. The boom tilt angle data includes the tilt angle of the first boom 4 in the vertical direction with respect to the horizontal plane. The boom IMU 64 outputs the boom tilt angle data to the attitude detection controller 68.

[0037] As shown in FIG. 1, the arm IMU 65 is arranged on the arm 7. The arm IMU 65 acquires arm tilt angle data indicating the tilt angle of the arm 7. The arm tilt angle data includes the tilt angle of the arm 7 in the vertical direction with respect to the horizontal plane. The arm IMU 65 outputs the arm tilt angle data to the attitude detection controller 68.

[0038] As shown in FIG. 1, the bucket IMU 66 is arranged on the link 22 connected to the bucket 8. The bucket IMU 66 acquires bucket tilt angle data indicating the tilt angle of the bucket 8. The bucket tilt angle data includes the tilt angle of the bucket 8 in the vertical direction with respect to the horizontal plane. The bucket IMU 66 outputs the bucket tilt angle data to the attitude detection controller 68.

[0039] The angle sensor 67 is mounted on the working machine 1. The angle sensor 67 detects the offset angle of the working machine 3. The offset angle of the working machine 3 is the offset angle of the second boom 5 with respect to the first boom 4. The angle sensor 67 detects the offset angle of the second boom 5 with respect to the first boom 4. The angle sensor 67 is arranged on the first boom 4.

[0040] As shown in FIG. 4, a protruding piece 10 is provided on the left part of the first boom 4. The angle sensor 67 is fixed to the protruding piece 10 by, for example, a bolt. The offset stay 9 is rotatably connected to the protruding piece 10 by a pin 27. In the embodiment, the rotation axis of the angle sensor 67 is arranged at a concentric position with the pin 27. One end of the lever link 28 is fixed to the upper part of the rotation axis of the angle sensor 67. A long hole 29 is formed at the other end of the lever link 28. A bolt 30 inserted through the long hole 29 is coupled to a nut fixed to the upper surface of the offset stay 9. The rotation axis of the angle sensor 67 may be arranged at a concentric position with the offset pin 18.

[0041] When the offset stay 9 swings left and right about the pin 27, the lever link 28 swings left and right, and the rotation axis of the angle sensor 67 rotates. When the rotation axis of the angle sensor 67 rotates, the offset angle of the second boom 5 is detected by the angle sensor 67. The angle sensor 67 outputs the detected value of the offset angle of the second boom 5 to the attitude detection controller 68.

[0042] The attitude detection controller 68 has a processor such as a CPU (Central Processing Unit) and a main memory including a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory). The storage device 69 is an example of a non-transitory processor-readable recording medium. The storage device 69 records computer instructions that are executable by the processor and control the working machine 1.

[0043] The attitude detection controller 68 calculates the attitude of the working machine 3 based on the vehicle tilt angle data, boom tilt angle data, arm tilt angle data, and bucket tilt angle data. The attitude of the working machine 3 includes a boom angle indicating the tilt angle of the first boom 4 with respect to the vehicle body 2, an arm angle indicating the tilt angle of the arm 7 with respect to the first boom 4, and a bucket angle indicating the tilt angle of the bucket 8 with respect to the arm 7.

[0044] The memory device 69 stores shape data indicating the shape of the vehicle body 2, shape data indicating the shape of the working machine 3, current situation terrain data indicating the current situation terrain of the work site, and design terrain data indicating the target shape of the work site.

[0045] The shape data of the vehicle body 2 indicates the positional relationship between each of the GNSS antennas 62A and 62B and the reference position of the vehicle body 2. The shape data of the vehicle body 2 indicates the positional relationship between the reference position of the vehicle body 2 and the boom pin 17.

[0046] The shape data of the working machine 3 includes the dimensions of the working machine 3. The attitude detection controller 68 detects bucket position data from the vehicle position data acquired by the GNSS receiver 61 based on the vehicle inclination angle data, boom inclination angle data, arm inclination angle data, bucket inclination angle data, and offset angle data. The bucket position data indicates the cutting edge position of the bucket 8.

[0047] FIG. 7 is a diagram showing a guide screen 72 displayed on the display input device 70 according to the embodiment. The attitude detection controller 68 displays the guide screen 72 shown in FIG. 7 on the display input device 70 based on the current situation terrain data, the design terrain data, and the shape data. As shown in FIG. 7, the guide screen 72 shows the current situation terrain 73, the design terrain 74, and the position of the working machine 1. The shape data of the working machine 3 includes shape data indicating the shape of the bucket 8. The attitude detection controller 68 shows the position of the bucket 8 with respect to the current situation terrain 73 and the design terrain 74 on the guide screen 72 based on the shape data of the bucket 8 and the bucket position data.

[0048] The display input device 70 displays the guide screen 72 based on an input instruction from the operator. The display input device 70 communicates with the attitude detection controller 68 through the Internet via the communication device 71. The display input device 70 is, for example, a tablet terminal. The communication device 71 connects the display input device 70 to the Internet. The communication between the display input device 70 and the communication device 71 may be performed either wired or wirelessly. The communication device 71 is, for example, a wireless LAN router.

[0049] [Offset Angle Calibration Method] Each of FIGS. 8 and 9 is a flowchart showing an offset angle calibration method according to an embodiment. The offset angle of the working machine 3 is calibrated by the offset angle calibration method.

[0050] In the embodiment, the offset angle calibration method includes a position information acquisition step (step S11) of using the total station TS to acquire the position information p1, p2, p3 of a predetermined position of the working machine 3 in a plurality of offset postures K1, K2, K3 in which only the offset in the left-right direction is performed with the working machine 3 fixed in a predetermined posture, a first offset angle calculation step (steps S12 to S33) of calculating the first offset angles θ1, θ2, θ3 in each of the offset postures K1, K2, K3 based on the position information p1, p2, p3, and a second offset angle for calibration to obtain the second offset angles θ of1 , θ of2 , θ of3 in each of the offset postures K1, K2, K3 based on the detection values in the plurality of offset postures K1, K2, K3 by the angle sensor 67, and an error calculation step (step S36) of calculating the measurement errors e1, e2, e3 of the angle sensor 67 based on the first offset angles θ1, θ2, θ3 and the second offset angles θ of1 , θ of2 , θ of3 in each of the offset postures K1, K2, K3.

[0051] The first offset angle calculation step includes a plane calculation step (step S12) of calculating an offset plane U where the distances from a plurality of predetermined positions p1, p2, p3 are minimized based on the position information of the predetermined positions p1, p2, p3 of the working machine in a plurality of offset postures K1, K2, K3; a coordinate conversion step (step S31) of converting the coordinates of a plurality of projection positions p'1, p'2, p'3 obtained by projecting the plurality of predetermined positions p1, p2, p3 onto the offset plane U from the coordinate system of the total station TS to the coordinate system of the offset plane U; a circle calculation step (step S32) of calculating a circle on the offset plane U where the error from a plurality of projection positions ps1, ps2, ps3 is minimized in the coordinate system of the offset plane U; and an angle calculation step (step S33) of calculating the rotation angles θ1, θ2, θ3 of each projection position ps1, ps2, ps3 on the circle and setting the rotation angles θ1, θ2, θ3 as the first offset angles in the offset postures K1, K2, K3 corresponding to the projection positions ps1, ps2, ps3.

[0052] Hereinafter, the details of each step from step S10 to step S30 will be described.

[0053] FIG. 10 is a plan view showing a state in which the working machine 3 according to the embodiment is moved to a plurality of offset postures K1, K2, K3 and the coordinates of the boom top are measured by the total station TS. The total station TS is a measuring device arranged outside the working machine 1. The total station TS acquires the position information of a predetermined position of the working machine 3. In the embodiment, the predetermined position of the working machine 3 is the position of the boom top which is the tip of the second boom 5. The total station TS acquires the position information of the boom top.

[0054] A prism is attached to the boom top which is the tip of the second boom 5. The total station TS can measure the coordinates of the boom top by receiving the reflected wave from the prism attached to the boom top.

[0055] In step S11 of step S10, with the working machine 3 fixed in a predetermined posture, the position information of the boom top of the working machine 3 is acquired using the total station TS in a plurality of offset postures where only the offset in the left - right direction is performed. In step S11, only the second boom cylinder 24 is extended and retracted without extending and retracting the first boom cylinder 23, the arm cylinder 25, and the bucket cylinder 26 respectively. That is, with the boom angle, the arm angle, and the bucket angle fixed, only the second boom 5 is operated, and the reflected wave from the prism attached to the boom top is received by the total station TS to measure the coordinates of the prism.

[0056] For example, as shown in FIG. 10, the coordinates of the boom tops at points p1, p2, p3 in a plurality of offset postures K1, K2, K3 are measured. Point p1 is the position of the boom top in the offset posture K1 (right end) which is the mechanical limit when the working machine 3 is offset to the right with respect to the slewing body 11. Point p2 is the position of the boom top in the offset posture K2 (neutral posture) where the working machine 3 is arranged parallel to the front - rear direction of the slewing body 11 in plan view. Point p3 is the position of the boom top in the offset posture K3 (left end) which is the mechanical limit when the working machine 3 is offset to the left with respect to the slewing body 11.

[0057] FIG. 11 is a diagram showing a display screen of the display input device 70 during offset angle calibration according to the embodiment. In step S11, an offset angle calibration screen 80 as shown in FIG. 11 is displayed on the display input device 70. The offset angle calibration screen 80 instructs the operator to assume an offset posture as displayed on the screen. The offset angle calibration screen 80 includes a first screen 81, a second screen 82, a third screen 83, an X coordinate input section 84, a Y coordinate input section 85, a Z coordinate input section 86, and a sensor value display section 87. The first screen 81 displays a side view of the working machine 3. The second screen 82 displays a perspective view of the working machine 1. The third screen 83 displays a plan view of the working machine 1. A prism 91 is shown on each of the first screen 81, the second screen 82, and the third screen 83. A total station TS is shown on the third screen 83, and the XYZ coordinates at the total station TS are shown. The detection value of the angle sensor 67 is displayed on the sensor value display section 87.

[0058] The operator operates the operating device 47 to drive the second boom cylinder 24 so as to visually follow the offset angle calibration screen 80 shown in FIG. 11 and rotate the working machine 3 with respect to the slewing body 11 to assume the offset posture K1. Then, the position coordinates of the prism 91 are detected by the total station TS. The XYZ coordinates detected by the total station TS are input by the operator into the X coordinate input section 84, the Y coordinate input section 85, and the Z coordinate input section 86. The input XYZ coordinates are output to the attitude detection controller 68.

[0059] Similarly, on the offset angle calibration screen 80, the operator is instructed to set the working machine 3 to the offset posture K3. The operator offsets the working machine 3 to the left with respect to the slewing body 11 until the mechanical limit is reached while keeping the boom angle, arm angle, and bucket angle fixed according to the offset angle calibration screen 80. As a result, the working machine 3 assumes the offset posture K3. Then, the total station TS detects the position coordinates of the prism 91. The XYZ coordinates detected by the total station TS are input by the operator to the X coordinate input section 84, the Y coordinate input section 85, and the Z coordinate input section 86. The input XYZ coordinates are output to the attitude detection controller 68.

[0060] Similarly, on the offset angle calibration screen 80, the operator is instructed to set the working machine 3 to the offset posture K2. The operator offsets the working machine 3 with respect to the slewing body 11 until the neutral position is reached while keeping the boom angle, arm angle, and bucket angle fixed according to the offset angle calibration screen 80. As a result, the working machine 3 assumes the offset posture K2. Then, the total station TS detects the position coordinates of the prism 91. The XYZ coordinates detected by the total station TS are input by the operator to the X coordinate input section 84, the Y coordinate input section 85, and the Z coordinate input section 86. The input XYZ coordinates are output to the attitude detection controller 68.

[0061] Through the above operations, the attitude detection controller 68 obtains the values of the XYZ coordinates of the total station TS at the points p1, p2, p3 at the boom top in the offset postures K1, K2, K3. The order of attitude detection for the offset postures K1, K2, K3 is not limited to this.

[0062] Next, as shown in step S12 of FIG. 8, the attitude detection controller 68 calculates the offset operation plane using the least squares method. In step S12, based on the position information of the boom top in a plurality of offset postures K1 to K3, an offset operation plane with the minimum distance from a plurality of boom tops is calculated.

[0063] Specifically, as shown in equations (1) and (2), let the XYZ coordinates of the total station TS at points p1 to p3 be pi, and its centroid vector be g.

[0064]

Number

[0065]

Number

[0066] If the equation of the offset plane U where the distance from each point of point pi is minimized is the following equation (3), then a, b, and c are obtained using the least squares method from the following equation (4).

[0067]

Number

[0068]

Number

[0069] Let the normal vector of the offset plane U be N, the distance from the origin be h, and the unit vector of N be n. Then N is represented by the following equation (5), n is represented by the following equation (6), and h is represented by the following equation (7).

[0070]

Number

[0071]

Number

[0072]

Number

[0073] FIG. 12 is a diagram for explaining an offset angle calibration method according to an embodiment. Next, in step S13, as shown in FIG. 12, the attitude detection controller 68 projects the points pi (i = 1, 2, 3) onto the offset plane U to create the points p’i (i = 1, 2, 3). The points p’i projected onto the offset plane U can be expressed by the following equation (8).

[0074]

Equation

[0075] Next, in step S21 of step S20 (creation of offset coordinates), the attitude detection controller 68 sets the point obtained by translating the offset points p’i (i = 1, 2, 3) only by the point p’1 as the point p”i. This is to set p’i as the origin in the offset coordinate system.

[0076]

Equation

[0077] FIG. 13 is a diagram for explaining an offset angle calibration method according to an embodiment. Next, in step S22, as shown in FIG. 13, the attitude detection controller 68 calculates the unit vector sx of the p”1→p”3 vector as the x-axis of the offset plane U. The unit vector sx is represented by the following equation (10).

[0078]

Equation

[0079] Next, in step S23, as shown in FIG. 13, the attitude detection controller 68 sets the cross product sy of sx and n (the unit vector of the normal vector N in step S12) as the y-axis of the offset plane U as shown in the following equation (11). Further, the attitude detection controller 68 sets n as the z-axis of the offset plane U as shown in the following equation (12).

[0080]

Number

[0081]

Number

[0082] Next, in step S24, the attitude detection controller 68 calculates a matrix Q for converting from the coordinate system of the total station TS to the coordinate system of the offset plane U. The matrix Q is represented by the following equation (13).

[0083]

Number

[0084] Next, in step S31 of step S30 (offset angle calculation), the attitude detection controller 68 uses the following equation (14) to set the point obtained by converting the offset point p”i to the coordinate system of the offset plane U as the offset conversion point psi.

[0085]

Number

[0086] As described above, the coordinates of the points p’i indicating the plurality of projection positions obtained by projecting the points pi indicating the positions of the plurality of boom tops onto the offset plane U are converted from the coordinate system of the total station TS to the coordinate system of the offset plane U.

[0087] Next, as shown in FIG. 9, in step S32, the attitude detection controller 68 uses the least squares method to calculate a circle in the offset plane U in which the error from the plurality of offset conversion points psi is minimized, with sx as the x-axis and sy as the y-axis. The circle is represented by the following equation (15).

[0088]

Number

[0089] A, B, and C in formula (15) can be obtained using the following formula (16).

[0090]

Equation

[0091] FIG. 14 is a diagram for explaining the offset angle calibration method according to the embodiment. Here, as shown in FIG. 14, if the center coordinates of the circle are so(a, b) and the radius is r, the relationships between a, b, and r and A, B, and C can be expressed by the following formulas (17), (18), and (19).

[0092]

Equation

[0093]

Equation

[0094]

Equation

[0095] Thus, the center coordinates so(a, b) and the radius r of the circle are obtained.

[0096] FIG. 15 is a diagram for explaining the offset angle calibration method according to the embodiment. Next, in step S33, the attitude detection controller 68 calculates the offset angle θi (the first offset angle) from the offset conversion point ps2 to the offset conversion points ps1 and ps3. As shown in FIG. 15, let the vector from the offset center so to psi be qi. q2 is in the neutral attitude. θi (i = 1, 2, 3) can be obtained by the following formula (20).

[0097] [Number]

[0098] On the one hand, in step S34, the attitude detection controller 68 acquires offset angle data indicating the offset angle (second offset angle) in each of the offset attitudes K1, K2, K3 based on the detection values at the plurality of offset attitudes K1, K2, K3 by the angle sensor 67. That is, the attitude detection controller 68 acquires the offset angle data which is the detection value by the angle sensor 67 in the offset attitudes K1, K2, K3. These offset angle data may be acquired by the angle sensor 67 when the working machine 3 is swung with respect to the swing body 11 to the offset attitudes K1, K2, K3 in step S11.

[0099] Next, in step S35, the attitude detection controller 68 calculates the offset angle in each of the offset attitudes K1, K2, K3 from the offset angle data in the offset attitudes K1, K2, K3. Here, the offset angle θ of (second offset angle) is θ of1 , θ of2 , θ of3 and so on.

[0100] Next, in step S36, the attitude detection controller 68 calculates the angle error ei (i = 1, 2, 3) in each of the offset attitudes K1, K2, K3. The angle error ei is calculated by the following formula (21).

[0101] [Number]

[0102] Next, in step S40, the attitude detection controller 68 creates an offset angle error table T. (θ of1、 e1), (θ of2、 e2), (θ of3、Assuming that the line segment connecting (e3) is y = ai × x + bi, ai and bi are represented by the following equation (22).

[0103]

Number

[0104] FIG. 16 is a diagram showing an offset angle error table T created by the offset angle calibration method according to the embodiment. The attitude detection controller 68 creates an offset error correlation table T based on the first offset angles θ1, θ2, θ3 and the second offset angles θ of1 , θ of2 , θ of3 at a plurality of offset postures K1, K2, K3. The horizontal axis in FIG. 16 indicates the offset angle (deg) calculated from the angle sensor 67. As shown on the horizontal axis, the offset angle to the right from the offset posture K2, which is the neutral posture, is indicated as negative, and the offset angle to the left from the offset posture K2 is indicated as positive.

[0105] The offset angle error table T shown in FIG. 16 is stored in the storage device 49. The attitude detection controller 68 corrects the offset angle of detected by the angle sensor 67 based on the offset angle error table T to calculate the corrected offset angle θ of '. The attitude detection controller 68 corrects the offset angle θ of calculated from the offset angle data, which is the detection value of the angle sensor 67, using the offset angle error table T to calculate the corrected offset angle θ of ' as shown in the following equation (23).

[0106]

Number

[0107] For example, the offset angle θ of obtained from the angle sensor 67 is θ of1 and θ of2When it is between them, the error is calculated using the straight line M1 of y = ai × x + bi (see Fig. 16), and the error-corrected offset angle θ of ’ is calculated by subtracting the error from the obtained offset angle.

[0108] Note that step S11 corresponds to an example of a position information acquisition step. Steps S12, S13, S21 to S24, and S31 to S33 correspond to an example of a first offset angle calculation step. Steps S34 and S35 correspond to an example of a calibration second offset angle acquisition step. Step S40 corresponds to an example of a creation step. Step S12 corresponds to an example of a plane calculation step. Steps S20 and S31 correspond to an example of a coordinate conversion step. Step S32 corresponds to an example of a circle calculation step. Step S33 corresponds to an example of an angle calculation step. Step S36 corresponds to an example of an error calculation step. Note that the offset angle calibration system includes a total station TS, an angle sensor 67, and an attitude detection controller 68.

[0109] [Method for calculating the cutting edge position of the bucket] Next, a method for calculating the cutting edge position of the bucket 8 will be described. The attitude detection controller 68 can calculate the cutting edge position of the bucket 8 based on predetermined parameters.

[0110] Note that the method for calculating the cutting edge position of the bucket 8 described below is applicable not only to the offset type working machine having the offset boom described in the above embodiment, but also to a working machine having a swing type boom as disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-348899, and a working machine having a two-piece boom when calculating the cutting edge position of the bucket.

[0111] Fig. 18 is a side view schematically showing the working machine 1 according to the embodiment. Fig. 19 is a plan view schematically showing the working machine 1 according to the embodiment. As shown in Figs. 18 and 19, positions A, B, C, D, E, F, G, H, and I are defined on the working machine 1.

[0112] Position A is the central position of the revolving body 11. Position B is the rotation center when the boom is rotatable about a rotation axis parallel to the rotation axis RX of the revolving body 11. In the offset boom, position B is the rotation center of the revolving body 11. In the swing boom, position B is the swing center of the swing boom. Position C is the position of the base end portion of the first boom 4, and in the embodiment, it is the position of the boom pin 17. Position D is the position of the tip end portion of the first boom 4, and in the embodiment, it is the position of the offset pin 18. Position E is the position of the base end portion of the second boom 5, and in the embodiment, it is the position of the offset pin 18. In the offset boom, position D and position E are the same position. Position F is the position of the tip end portion of the second boom 5, and in the embodiment, it is the position of the bracket pin 19. Position G is the position of the base end portion of the arm 7, and in the embodiment, it is the position of the arm pin 20. Position H is the position of the tip end portion of the arm 7, and in the embodiment, it is the position of the bucket pin 21. Position I is the cutting edge position of the bucket 8.

[0113] The attitude detection controller 68 can calculate the cutting edge position of the bucket 8 based on predetermined parameters. The predetermined parameters include vehicle position data detected by the GNSS receiver 61, vehicle tilt angle data detected by the body IMU 63, boom tilt angle data detected by the boom IMU 64, arm tilt angle data detected by the arm IMU 65, bucket tilt angle data detected by the bucket IMU 66, shape data of the vehicle body 2 stored in the storage device 69, and shape data of the working machine 3 stored in the storage device 69.

[0114] The parameters for calculating the cutting edge position of the bucket 8 include the respective dimensions of the first boom 4, the second boom 5, the swing bracket 6, the arm 7, and the bucket 8, the angle of the first boom 4 with respect to the slewing body 11, the angle of the second boom 5 with respect to the first boom 4, the angle of the swing bracket 6 with respect to the second boom 5, the angle of the arm 7 with respect to the swing bracket 6, and the angle of the bucket 8 with respect to the arm 7. The parameters are defined as follows, for example.

[0115] The first boom length L 1 is the distance between position C and position D. The second boom length L offsetboom is the distance between position E and position F. Although not shown in FIGS. 18 and 19, the second boom height L used in the following equation (28) 2ndboom is the distance between position D and position E. As described above, in the offset boom, position D and position E are the same position, so the second boom height L in equation (28) 2ndboom is zero. The swing bracket length L offsetboomtop is the distance between position F and position G.

[0116] Although not shown in FIGS. 18 and 19, the coordinate x used in the following equation (26) swingcenter is the X coordinate of position B. The coordinate y swingcenter is the Y coordinate of position B.

[0117] The coordinate x boomfoot is the X coordinate of position C. The coordinate y boomfoot is the Y coordinate of position C. The coordinate z boomfoot is the Z coordinate of position C.

[0118] The distance x offsetboom is the distance in the X-axis direction of the coordinate axis x between position E and position F e The distance x offsetboomtop is the distance in the X-axis direction between position F and position G.

[0119] Although not shown in FIGS. 18 and 19, the angle θ used in the following equation (26) swis the swing angle of the working machine on the swing boom. In the offset boom, since there is no swing angle, the angle θ in equation (26) sw is zero.

[0120] The angle θ 1 is the angle of the first boom 4 with respect to the slewing body 11. The angle θ' 1 is the angle of the second boom 5 with respect to the first boom 4 in a plane perpendicular to the rotation axis AX1. The angle θ offset is the angle of the second boom 5 with respect to the first boom 4 in a plane perpendicular to the offset axis BX1. The angle -θ offset is the angle of the swing bracket 6 with respect to the second boom 5 in a plane perpendicular to the offset axis BX2. The angle θ 2 is the angle of the arm 7 with respect to the line connecting the positions F and G of the swing bracket 6 in a plane perpendicular to the rotation axis AX2. The angle θ'' 1 is the angle between the line connecting the positions F and G and the line parallel to the second boom in a plane perpendicular to the rotation axis AX2.

[0121] Although not shown in FIGS. 18 and 19, the angle θ used in equation (28) described later 2PB is the angle formed by the first boom and the second boom in the two-piece boom. In the offset boom, the angle θ in equation (28) 2PB is zero.

[0122] The angle θ 3 is the angle of the bucket 8 with respect to the arm 7.

[0123] The coordinates of the position A of the slewing body 11 are obtained from the vehicle position data from the GNSS receiver 61. When obtaining the position I, which is the cutting edge position of the bucket 8, from the position A, which is the center position of the slewing body 11, it is calculated by the following equation (24).

[0124]

Equation

[0125] The conversion formula for obtaining position B from position A is expressed as the following formula (25). The conversion formula for obtaining position C from position B is expressed as the following formula (26). The conversion formula for obtaining position D from position C is expressed as the following formula (27). The conversion formula for obtaining position E from position D is expressed as the following formula (28). The conversion formula for obtaining position F from position E is expressed as the following formula (29). The conversion formula for obtaining position G from position F is expressed as the following formula (30). The conversion formula for obtaining position H from position G is expressed as the following formula (31). The conversion formula for obtaining position I from position H is expressed as the following formula (32). In the embodiment, the coordinates of each point are defined according to the forward kinematics by the homogeneous transformation matrix.

[0126]

Number

[0127]

Number

[0128]

Number

[0129]

Number

[0130]

Number

[0131]

Number

[0132]

Number

[0133]

Number

[0134] As described above, equations (24) to (32) are generalized equations applicable not only to offset type work machines having an offset boom, but also to work machines having a swing boom and work machines having a two-piece boom when calculating the cutting edge position of the bucket. In the embodiment, the work machine 3 is an offset type work machine having an offset boom. Therefore, in equations (24) to (32), the second boom height L 2ndboom is zero, the angle θ sw is zero, and the angle θ 2PB is zero.

[0135] [Parameter Calibration Method] The attitude detection controller 68 calibrates the parameters necessary for calculating the cutting edge position of the bucket 8. The attitude detection controller 68 calibrates the parameters based on the positions of the respective working points of the work machine 3 measured by the total station TS.

[0136] For example, due to the mounting error of the IMU and the aging deterioration of the work machine 3, etc., the cutting edge position of the bucket 8 calculated based on the above equations (24) to (32) may deviate from the original cutting edge position. The attitude detection controller 68 calculates the calibration value of the parameter based on the position information of the respective working points of the work machine 3 measured by the total station TS so that the cutting edge position of the bucket 8 calculated based on the above equations (24) to (32) coincides with the original cutting edge position.

[0137] FIG. 17 is a side view showing the working machine 1 when calibrating the parameters according to the embodiment. As shown in FIG. 17, when calibrating the parameters, the prism 91 is attached to eight locations of the working machine 1. The prism 91 is attached to each of the boom pin 17, the upper part of the offset pin 18, the lower part of the offset pin 18, the lower part of the bracket pin 19, the arm pin 20, the first part of the link 22, the second part of the link 22, and the bucket pin 21. The prisms 91 attached to the upper and lower parts of the offset pin 18 are arranged coaxially with the offset axis BX1. The prism 91 attached to the lower part of the bracket pin 19 is arranged coaxially with the offset axis BX2. The prism 91 attached to the arm pin 20 is arranged coaxially with the rotation axis AX2. The prism 91 attached to the bucket pin 21 is arranged coaxially with the rotation axis AX3.

[0138] As described with reference to FIG. 10, the prism 91 attached to the working machine 1 is measured by the total station TS. The working point of the working machine 3 measured by the total station TS includes the position of the prism 91.

[0139] In the embodiment, at least one of the prisms 91 is attached to the upper part of the offset pin 18. At least one of the prisms 91 is attached to the lower part of the offset pin 18. At least one of the prisms 91 is attached to the lower part of the bracket pin 19. The prisms 91 attached to the upper and lower parts of the offset pin 18 are arranged coaxially with the offset axis BX1. The prism 91 attached to the lower part of the bracket pin 19 is arranged coaxially with the offset axis BX2.

[0140] By measuring the prism 91 attached to at least one of the upper and lower parts of the offset pin 18 with the total station TS, the position information of the offset axis BX1 (the first offset axis) indicating the rotation axis of the first boom 4 and the second boom 5 is measured.

[0141] The prism 91 attached to the lower part of the bracket pin 19 is measured by the total station TS, whereby the position information of the offset axis BX2 (second offset axis) indicating the rotation axis of the second boom 5 and the swing bracket 6 is measured.

[0142] The prism 91 attached to the arm pin 20 is measured by the total station TS, whereby the position information of the rotation axis AX2 between the swing bracket 6 and the arm 7 is measured.

[0143] The prism 91 attached to the bucket pin 21 is measured by the total station TS, whereby the position information of the rotation axis AX3 between the arm 7 and the bucket 8 is measured.

[0144] Each of FIGS. 20 to 23 is a side view schematically showing the posture of the working machine 1 when the total station TS measures the prism 91 for calibration of the parameters according to the embodiment. The operator changes the working machine 1 to each posture shown in FIGS. 20 to 23 of the working device 3 of the working machine 1. The operator changes the posture of the working device 3 without turning the revolving body 11. The total station TS measures the position of each of the plurality of prisms 91 attached to the working machine 1.

[0145] The posture of the working device 3 is changed so that the working device elements (first boom 4, second boom 5, swing bracket 6, arm 7, and bucket 8) to which the IMU is attached are in at least two different postures (angles) with respect to each other. In the embodiment, since the boom IMU 64 is attached to the first boom 4, the first boom 4 is operated so as to be in at least two different postures (angles) with respect to each other. Since the arm IMU 65 is attached to the arm 7, the arm 7 is operated so as to be in at least two different postures (angles) with respect to each other. Since the bucket IMU 66 is attached to the bucket 8, the bucket 8 is operated so as to be in at least two different postures (angles) with respect to each other.

[0146] In the following description, the posture of the work machine 3 shown in FIG. 20 is appropriately referred to as the first posture, the posture of the work machine 3 shown in FIG. 21 is appropriately referred to as the second posture, the posture of the work machine 3 shown in FIG. 22 is appropriately referred to as the third posture, and the posture of the work machine 3 shown in FIG. 23 is appropriately referred to as the fourth posture.

[0147] Between the first posture and the second posture, the postures (angles) of the first boom 4 are different from each other. Between the second posture and the third posture, the postures (angles) of the arm 7 are different from each other. Between the third posture and the fourth posture, the postures (angles) of the bucket 8 are different from each other. Between the second posture and the fourth posture, the respective postures (angles) of the first boom 4, the arm 7, and the bucket 8 are different from each other.

[0148] Although not shown, a parameter calibration screen is displayed on the display input device 70. Similar to the offset angle calibration screen 80 described with reference to FIG. 11, the parameter calibration screen instructs the operator so that the work machine 3 assumes the postures shown in FIGS. 20 to 23.

[0149] The operator operates the operating device 47 so that the work machine 3 assumes the first posture, the second posture, the third posture, and the fourth posture according to the parameter calibration screen. Then, the position coordinates of the prism 91 are detected by the total station TS. The XYZ coordinates of the prism 91 detected by the total station TS are input by the operator to the display input device 70. The input XYZ coordinates are output to the posture detection controller 68.

[0150] In the embodiment, the parameters are corrected so that the positions of a plurality of working points of the working machine 1 to which the prism 91 is attached are at their original positions. In the offset boom, as the position information of the working points, the position information of the offset axis BX1 between the first boom 4 and the second boom 5 and the position information of the offset axis BX2 between the second boom 5 and the swing bracket 6 are measured by the total station TS, so that the parameters are properly corrected.

[0151] Furthermore, since the position information of the work point, that is, the position information of the rotation axis AX2 between the oscillating bracket 6 and the arm 7, and the position information of the rotation axis AX3 between the arm 7 and the bucket 8, is measured by the total station TS, the parameters are appropriately configured.

[0152] [Posture detection method] The attitude detection controller 68 detects the offset angle θ after the error correction calculated in step S40. of Using the signal ', the posture of the work machine 3 can be detected. Detecting the posture of the work machine 3 includes detecting the position of the blade tip of the bucket 8.

[0153] When detecting the attitude of the work machine 3, the attitude detection controller 68 acquires vehicle position data from the GNSS receiver 61, acquires vehicle inclination angle data from the main body IMU 63, acquires boom inclination angle data from the boom IMU 64, acquires arm inclination angle data from the arm IMU 65, and acquires bucket inclination angle data from the bucket IMU 66.

[0154] Next, the attitude detection controller 68 acquires the offset angle data from the angle sensor 67 and calculates the offset angle θ of Next, the attitude detection controller 68 calculates the boom angle, the arm angle, and the bucket angle from the vehicle inclination angle data, the boom inclination angle data, the arm inclination angle data, and the bucket inclination angle data.

[0155] Next, the posture detection controller 68 calculates the offset angle θ based on the offset angle error table T stored in the storage device 69. of The attitude detection controller 68 calculates the error e in the offset angle θ of By subtracting the error e from the of ' is calculated.

[0156] Next, the attitude detection controller 68 detects the vehicle position data, the vehicle inclination data, the boom angle, the arm angle, the bucket angle, and the offset angle θ after error correction.of Based on the shape data of the vehicle body 2 and the shape data of the working machine 3, the cutting edge position of the bucket 8 is calculated.

[0157] Next, the attitude detection controller 68 displays the guide screen 72 shown in FIG. 7 on the display input device 70 based on the current terrain data, the designed terrain data, the shape data of the vehicle body 2, the shape data of the working machine 3, and the detected cutting edge position of the bucket 8.

[0158] [Effect] As described above, according to the embodiment, the angle sensor 67 is calibrated based on the position information measured by the total station TS. Therefore, the measurement error of the offset angle of the working machine 3 is suppressed. Also, based on the position information measured by the total station TS, the parameters for calculating the cutting edge position of the bucket 8 are corrected. Therefore, the calculation error of the cutting edge position of the bucket 8 is suppressed. As a result, the cutting edge of the bucket 8 can move along the designed terrain.

[0159] [Another Embodiment] In the above-described embodiment, the functions of the attitude detection controller 68 may be divided into separate hardware (computers). Also, the functions of the attitude detection controller 68 and the functions of the main body controller 51 may be realized by one hardware (computer). [Explanation of Reference Numerals]

[0160] 1... Working machine, 2... Vehicle body (working machine body), 3... Working implement, 4... First boom, 5... Second boom, 6... Swing bracket, 7... Arm, 8... Bucket, 9... Offset stay, 10... Protruding piece, 11... Slewing body, 12... Traveling body, 12A... Crawler, 13... Blade, 14... Floor, 15... Driver's seat, 16... Roof, 17... Boom pin, 18... Offset pin, 19... Bracket pin, 20... Arm pin, 21... Bucket pin, 22... Link, 23... First boom cylinder, 24... Second boom cylinder, 25... Arm cylinder, 26... Bucket cylinder, 27... Pin, 28... Lever link, 29... Long hole, 30... Bolt, 41... Drive system, 42... Drive control system, 43... Drive source, 44... Hydraulic pump, 45A... First travel motor, 45B... Second travel motor, 46... Slewing motor, 47... Operating device, 48... Input device, 51... Body controller, 52... Memory device, 53... Control valve, 60... Attitude detection system, 61... GNSS receiver, 62A... GNSS antenna, 62B... GNSS antenna, 63... Body IMU, 64... Boom IMU, 65... Arm IMU, 66... Bucket IMU, 67... Angle sensor, 68... Attitude detection controller, 69... Memory device, 70... Display input device, 71... Communication device, 72... Guide screen, 73... Current terrain, 74... Designed terrain, 80... Offset angle calibration screen, 81... First screen, 82... Second screen, 83... Third screen, 84... X coordinate input part, 85... Y coordinate input part, 86... Z coordinate input part, 87... Sensor value display part, 91... Prism, AX1... Rotation axis, AX2... Rotation axis, AX3... Rotation axis, BX1... Offset axis (first offset axis), BX2... Offset axis (second offset axis).

Claims

1. An offset angle calibration method for calibrating the offset angle of a working machine of a work machine, comprising: a position information acquisition step of acquiring position information of a predetermined position of the work machine using a measuring device in a plurality of offset postures in which only an offset in the left-right direction is performed with the work machine fixed in a predetermined posture; a first offset angle calculation step of calculating a first offset angle in each of the offset postures based on the position information; a second offset angle acquisition step for calibration of acquiring a second offset angle in each of the offset postures based on detection values in a plurality of the offset postures by an angle sensor mounted on the work machine and detecting the offset angle of the work machine; an error calculation step of calculating a measurement error of the angle sensor based on the first offset angle and the second offset angle in a plurality of the offset postures. An offset angle calibration method.

2. The first offset angle calculation step includes: a plane calculation step of calculating a plane in which the distances from a plurality of the predetermined positions are minimized based on the position information of the predetermined position of the work machine in the plurality of offset postures; a coordinate conversion step of converting coordinates of a plurality of projection positions obtained by projecting the plurality of predetermined positions onto the plane from the coordinate system of the measuring device to the coordinate system of the plane; a circle calculation step of calculating a circle in the plane in which the error from a plurality of the projection positions is minimized in the coordinate system of the plane; an angle calculation step of calculating a rotation angle of each of the projection positions on the circle and setting the rotation angle as the first offset angle in the offset posture corresponding to the projection position. The offset angle calibration method according to Claim 1.

3. A posture detection method for detecting the posture of a working machine of a work machine, comprising: a second offset angle acquisition step of acquiring a second offset angle based on a detection value of an angle sensor mounted on the work machine and detecting the offset angle of the work machine; a corrected second offset angle detection step of detecting a corrected second offset angle based on the second offset angle of the offset angle calibration method according to Claim 1; a posture detection step of detecting the posture of the work machine using the detected corrected second offset angle. A posture detection method.

4. The working machine has a working machine main body to which the working machine is attachable so as to be offsettable in the left - right direction. In the second offset angle acquisition step, the angle sensor detects the offset angle of the working machine with respect to the working machine main body. The attitude detection method according to claim 3.

5. The working machine has a boom rotatably attached to the working machine main body in the vertical direction, an arm rotatably attached to the tip of the boom, and a bucket rotatably attached to the tip of the arm. The attitude detection step detects the cutting edge position of the bucket. The attitude detection method according to claim 4.

6. An offset angle calibration system for calibrating the offset angle of a working machine of a working machine, a measuring device that measures the position information of a predetermined position of the working machine in a plurality of offset postures in which only an offset in the left - right direction is performed with the working machine fixed in a predetermined posture, an angle sensor mounted on the working machine for detecting the offset angle of the working machine, a controller that calculates a first offset angle in each of the offset postures based on the position information, acquires a second offset angle in each of the offset postures based on the detection values in the plurality of offset postures by the angle sensor, and creates a correlation table based on the first offset angle and the second offset angle in the plurality of offset postures. Offset angle calibration system.

7. An attitude detection system for detecting the attitude of a working machine of a working machine, an angle sensor mounted on the working machine for detecting the offset angle of the working machine, a storage unit that stores the correlation table of the offset angle calibration system according to claim 6, a controller that corrects the offset angle detected by the angle sensor based on the correlation table and detects the attitude of the working machine using the corrected offset angle. Attitude detection system.

8. The working machine has a working machine main body to which the working machine is attachable so as to be offsettable in the left - right direction. The angle sensor detects the offset angle of the working machine with respect to the working machine main body. The attitude detection system according to claim 7.

9. The working machine has a boom rotatably attached to the working machine main body in the vertical direction, an arm rotatably attached to the tip of the boom, A bucket rotatably attached to the tip of the arm, and The controller detects the cutting edge position of the bucket. The attitude detection system according to claim 8.

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